Interview with Miguel San Martín: The Mind Behind NASA’s Sky Crane and Mars Landings

Engineering the Impossible

For decades, the greatest challenge in planetary exploration wasn’t getting to Mars—it was landing there. The thin atmosphere, unpredictable winds, and rough terrain made every touchdown a gamble. Yet thanks to the ingenuity of Miguel San Martín, Chief Engineer for Guidance, Navigation, and Control (GNC) at NASA’s Jet Propulsion Laboratory (JPL), that challenge gave rise to one of the most iconic engineering feats in modern spaceflight: the Sky Crane landing system.

Speaking from his home in Palm Springs, California, San Martín reflected on the journey that transformed a “crazy” idea into the defining moment of the Curiosity and Perseverance rover missions.

The Birth of the Sky Crane

When JPL set out to land the one-ton Curiosity rover on Mars, they faced a dilemma. Previous missions—like Pathfinder and the Mars Exploration Rovers—had relied on airbags, while the Viking and Phoenix landers used legs and retrorockets. But Curiosity was too massive for airbags and too tall for a legged lander. The team needed a new way to deliver their payload safely to the Martian surface.

That’s when San Martín and his colleagues proposed an audacious concept: suspend the rover beneath a rocket-powered descent stage and lower it on tethers like a helicopter lifting cargo. It was a radical reversal of the traditional lander architecture—rockets above, rover below.

“When we first proposed the Sky Crane,” San Martín said, “people either called us geniuses—or crazy.”

To earn NASA’s approval, JPL convened a panel of experts that included Apollo veterans and helicopter pilots. After days of technical presentations and simulations, the verdict came in: the Sky Crane was the right approach. “The engineer who designed the lunar module’s landing legs immediately got it,” San Martín recalled. “He told us, ‘This is the way to do it.’”

Incredibly, the system was never fully tested on Earth. “We modeled every component—the engines, the tethers, the control system—so well that we didn’t need a full test,” he explained. “The first time we used it was on Mars.”

Perseverance and the Power of Vision

Nearly a decade later, San Martín’s innovation would prove itself again on the Perseverance rover, which added a new capability: Terrain Relative Navigation (TRN). Using onboard cameras and preloaded maps, the rover compared its surroundings during descent and autonomously steered away from hazards.

“The challenge,” he said, “was speed. You have seconds to take an image, compare it to a map, and decide where to land.”

To make that possible, the JPL team used field-programmable gate arrays (FPGAs)—specialized electronics capable of ultra-fast processing. It wasn’t simple: “You can’t just write C code for them,” San Martín said. “You program at the firmware level. But that speed is what made landing in Jezero Crater possible.”

Thanks to TRN, Perseverance touched down just 120 feet from a field of boulders that could have destroyed it—a precision unimaginable just years earlier.

Lessons from a Lifetime in Engineering

When I asked what skills young engineers should develop to contribute to future Entry, Descent, and Landing (EDL) or GNC systems, San Martín didn’t hesitate: “Be curious—and talk across disciplines.”

He explained that the Sky Crane’s success was rooted in collaboration between mechanical and control engineers, two groups that “sometimes don’t even talk.” That intersection, he said, “is where the greatest ideas happen.”

He also stressed the value of breadth over specialization early in one’s career. “I studied electronics, software, physics, and math. That let me speak many technical languages and connect ideas others couldn’t.”

But above all, he emphasized passion and adaptability: “Find something you love and that you’re good at. Don’t chase a career ladder—just focus on being great at what excites you right now. The doors will open.”

Beyond Equations: The Human Side of Innovation

In a reflection that resonated deeply with me, San Martín also emphasized the power of communication.

“As engineers, we often think math and physics are enough,” he said. “But to architect systems—to convince others of your vision—you must communicate clearly. It’s fundamental.”

He admitted that early in his education, he undervalued writing and speaking. “I used to think, ‘I don’t need this—I’m an engineer.’ I was wrong,” he said. “Being able to express ideas precisely can change everything.”

It’s advice that echoes across every conversation I’ve had through World of Aerospace: great engineering isn’t just about equations—it’s about connecting people and ideas.

A Legacy of Inspiration

From Viking to Pathfinder, Curiosity, and Perseverance, Miguel San Martín’s fingerprints are on the milestones that define humanity’s exploration of Mars. Yet his story is as much about humility as it is about history.

“I never planned a career,” he said simply. “I just did what was fun and meaningful. If you do that—and you do it well—the path finds you.”

As I wrapped up our conversation, I couldn’t help but think about what he represents: a reminder that engineering’s highest calling isn’t just to build—it’s to believe.